Multiple impregnating device for paper manufacture



June 16, 1936.

I.J.NOV AK MULTIPLE IMPREGNATING DEVICE FOR PAPER MANUFACTURE FiledMarch 5, 1934 2 Sheets-Sheet l Jun 16, 1936. I. J. NOVAK 2,044,912

MULTIPLE IMPREGNATING DEVICE FOR PAPER MANUFACTURE Filed March 5, 1934 2Sheets-Sheet? 132M??? for 1206107 I 1 01/0111 :Pii sylza Patented June16, 1936 UNITED STATES MULTIPL; IMPREGNATING DEVICE FOR APEB MANUFACTURE' Izador J. Novak, Bridgeport, 001111., assignor toRaybestos-Manhattan, Inc., Bridgeport, 001111., a corporation of NewJersey v Application March 5, 1934, Serial No. 714,118

7 Claims. (01. 92-40) This invention relates to improvements in themanufacture of paper, board, or similar felted, fibrous structureswherein modifying materials suspended or dissolved in water, such assizes, binders, water-proofings, etcetera, are introduced into the wetweb before substantial drying thereof, whereby the felted structure,when dried,

contains the desired modifying materials uni-' formly distributedthroughout the felted structure.

In its broad aspects, the invention relates to a method and apparatusfor felting fibers into a wet web and impregnating said wet web in aprogressive continuous operation.

In my co-pending application, Serial No. 681,- 056, I have described theadvantages and desirability of introducing modifying materials suspendedor dissolvedin water into a newly formed continuous wet web beingcontinuously removed from a paper forming machine, before substantialdrying thereof, and have described a saturating machine therefor andexplained its use. The saturating machine therein shown is placed in aconventional paper machine line,and the continuous wet web, after beingfelted and formed, is threaded from the web forming machine directly tothe saturating machine.

The present invention is directed to an improvement in the operationtherein described and in its preferred embodiment comprises thecombination, with a paper forming machine, of means for passing thenewly felted web being continuously removed from the web forminginstrumentality, and while still wet, through a series of impregnatingbaths, and means, following each bath, for removing the excess liquidfrom the web.

In said co-pending application I have described a process and apparatusfor impregnating the newly felted wet web wherein the web, after contactwith an excess of aqueous impregnating material, tends to swell anddistend, whereby the liquid impregnant enters between the fibers of theweb, displacing the air and some of the water existing between thefibers of the web. Thus, the web is impregnated and on drying acquiresthe advantages characteristic of this type of impregnation.

Certain stocks, however, due to their method of preparation, do notquickly distend and absorb even very fluid saturants when immersedtherein for a short period, such as is necessary in running atcommercial speed. Such stocks, for example, may be highly hydratedcellulose fiber webs, webs containing any considerable proportion ofsizing materials, or webs containing gelatinous animal cate, 10%gluesolution, 5% viscose.

fibers or the like, or in paper making term, slow webs. Furthermore,even relatively loose webs do not distend rapidly in viscous saturantssuch as, for example, 60% latex, 40 Baum sodium sili- Also, in somecases where the web does distend, suspensions of fillers contained inthe impregnating fluid do not enter as quickly as might be desired,especially where the suspended filler particles are relatively large.

In my co-pending application above referred to it will be noted that theweb may be allowed to remain in the impregnating bath for a longerperiod or the web may be run thinner, but these methods may not alwaysbe desirable in rapid commercial operation.

I have found that another phenomenon inherent in the operation of saidco-pending application also tends to improve uniformity of im--pregnation to a considerable extent. This is the couching which takesplace after the web passes through the impregnating bath due to theaction of the stripper roll which is positioned in the impregnating tankand the action of the squeeze rolls which remove the excess of aqueousliquid and allow the sheet to be built up into multiple plies or to becarried forward to roll dryers.

In adapting this inventive concept to the more thorough impregnation ofdense or gelatinous wet webs and to the use of viscous saturants andsluggish filler suspensions;'according to the present invention, I passthe web through a series of spaced impregnating baths in'combinationwith single or multiple couching between each impregnating bath.

My invention, briefly described, comprises a series of impregnatingbaths, an impregnating roll rotatably positioned adjacent each bath, aportion of the surface of each roll being immersed in each bath, astripper roll associated with each impregnating roll, an endlessforaminated conveyor for carrying a wet fibrous web adapted to passaround that portion of each impregnating roll which is immersed in thebath, and squeeze rolls following each bath between which said conveyorand fibrous web pass.

Thus, the web may be led through the first bath under conditions whichwould, on drying, result in a web having only a small residual saturantcontent but wherein the web has complete uniformity of saturation. It iscouched by the stripper roll acting against the impregnating roll onleaving the bath in the presence of an excess of impregnating liquid,then again pressed between squeeze rolls to reduce the excess ofimpregnating liquid,

both of which operations subject the web and the contained impregnatingliquid to mechanical pressure, thereby distributing the impregnatingliquid more thoroughly. Furthermore, the natural resiliency of the webcauses it to be condensed under pressure and to expand again when thepressure is released, which also aids in the more even distribution ofthe material carried in the saturant. The passage between the squeezerolls reduces the liquid content of the web and on its subsequentpassage into the next impregnating bath of higher concentration orviscosity it absorbs additional impregnating liquid, which may be of atype less readily saturable in a fresh previously unsaturated web, andwith further couching and pressing the second impregnating liquid isagain mechanically forced in and around the fibres.

The eifects of such multiple impregnation, couching and pressing areseveral. First, combinations of web and impregnating materials which arerelatively difiicult to combine by a single immersion are more easilycombined in plural immersions. Second, while the web previous to thefirst immersion contains water alone, there is a limit set by variousconditions, such as web characteristics, the characteristics of theimpregnating material, speed of travel .of the web through the papermachine, etc., to the amount of impregnating material which might beintroduced into it as the fresh web water is never wholly displaced bythe irnpregnating material. However, after couching and pressing, theweb contains a large proportion of impregnating material in addition tosome of the original water and on its entrance into the second bath,relatively little water need be displaced and the web on leaving thesecond and succeeding baths contains a much higher proportion ofimpregnating material. Depending on the nature of the web, impregnatingmaterial and speed. a suitable manner of impregmating and couchingstages may be used so that the web may contain substantially fullstrength impregnating material.

In the case of highly hydrated webs which would not saturate withcertain viscous impregnants, for example 40% latex, but would merelysurface-coat, the series of operations comprises leading the web firstinto a sufliciently dilute saturant liquid of the same composition asthe saturant finally desired in the web. This dilute saturant will causethe web to distend and will therefore impregnate it without surfaceprecipitation. The succeeding steps include saturation in successivelymore concentrated latices with intermediate couching and removal ofexcess liquid until the final saturant is distributed within the webwhereupon the'web may be in condition for drying. For example, in athree step saturation the first saturant may have a concentration of10%, the second 25%, and the third 40%. The initial saturation may be acomplete saturation and must separate the fibres and distend the web, sothat subsequent saturation may be of equal thoroughness.

Itwillbe appreciatedthatwhereas the fresh web, for example, whenhydrated fibres are used, may be sufficiently close packed and of suchfine liquid pore space and adhesiveness of fibres as to resistpenetration and separation of fibres by a relatively viscous liquid, ifseparation of these fibres is once accomplished by a thin dilutesaturant of the composition desired or of any suitably actingcomposition the presence of the new material between the fibres operatesto make them more easily separable on subsequent immersion in saturantliquids. Further saturations will of course, increase the ease ofseparation until the web is capable of saturation in the liquid desiredas final residual saturant. By this means the tendency of certain 5suspensions and emulsions to filter and divide into a more fluid and amore viscous state (the latter concentrating on the web surface) may beavoided and saturation accomplished.

Other objects and advantages will be apparent 10 from the accompanyingdrawings and following detail description.

In the drawings, Figs. 1 and 1a comprise side elevational views of thedevice of my invention.

Fig. 2 is an enlarged sectional elevation of one 15 of the impregnatingunits.

Referring in detail to the drawings, I indicates a frame which isadapted to support the various impregnating units and pressing unitscomprising my invention. At one end of the frame I a block 0 2 may beslidably mounted, said block being threadedly engaged with screw 3.Screw 3 may be journalled at one end in support 4, which may be mountedupon frame I and the opposite end of said screw may be journalled insupport 5 which 25 may be mounted at the end of frame I. A collar 6 maybe positioned upon screw 3 and may be keyed thereto, said collar beingadapted to abut support 5. A collar 1 may also be keyed to theprojecting end of screw 3 and is adapted in con- 30 junction with collar8 to prevent longitudinal movement of screw 3.

A hand wheel 8 may comprise an integral por-- tion of collar I, saidhand wheel being provided with handle 9 whereby screw 3 may be rotated35 to move block 2 longitudinally along the end portion of frame I. Asprocket wheel I 0 may be provided on the surface of collar 1 wherebyscrew 3 may be rotated at a point remote from the projecting end of saidscrew, or said screw may be rotated by power means (not shown). A shaftI I may be journalled in block 2 and may be adapted to carry cylinder ordrum I2, over which an endless screen I3 is adapted to pass. Screen I3is preferably constructed of stainless steel or other non-corrodingmetal and may be of mesh ranging between 20 and 80 openings to thesquare inch. It can readily be seen that by rotating screw 3 and therebymoving block 2, the tension of screen I3 may be adjusted.

Screen I3 in its forward travel after passage around drum I2 is adaptedto carry a newly formed wet fibrous web I4 which may be continuouslypassed to screen I3 from a paper making machine (not shown). The wet webI4 carries as much moisture as is carried by a web coming from the pressunits of a Fourdrinier machine prior to passing the web to the driers.Of course, the quantity of moisture contained in the web I4 will dependupon the characteristics of the fibres constituting the web, the type ofimpregnating material with which the web is adapted to be treated, thespeed of the machine and the characteristics desired in the ultimateproduct. Screen I3 after passing over drum I2 may travel around drum I5which may be mounted upon shaft I6 which, in turn, may be journalled inframe I.

An impregnating roll I! mounted upon shaft I8, which latter may besupported in bearings I9, may be positioned adjacent drum I5. Roll I!may be of hollow construction, its peripheral surface comprising screen20 which may be of a mesh similar to that of wire I3. The screen 20 maybe supported at each end of the roll by means of spider 2I. A vat 22 maybe positioned immediately beneath roll IT, a portion of said roll beingadapted during rotation thereof to dip into the interior of said vat.Vat 22 may be adapted to carry a quantity of impregnating material,coating material, sizing material or any other substance with which itis desired to treat web I3.

Referring particularly to Fig. 2, it can be seen that when screen I3 andweb I4 pass over drum I5, web I4 will be confined between screen I3 and.screen 20 comprising the peripheral surface of roll I'I. Confined inthis manner between the two foraminous surfaces mentioned, web I4 ispassed through the bath carried in vat 22.

As has been hereinbefore described, web I4 contains an appreciablequantity of water. and when immersed in the liquid impregnant comprisingthe bath would tend to disintegrate. However, said web, being positivelyconfined between the foraminated surfaces mentioned, will notdisintegrate nor will its fibrous formation be disturbed. However, whensaid web passes through the bath, its entire surface area is exposed tothe liquid comprising the bath and, hence, a degree'of substitutiontakes place, that is, the material comprising the bath tends to replacea portion of the water originally present in the web, and the airsurrounding the fibres of the web' is replaced by liquid impregnant.

Bars 23 may be mounted upon. each side of frame I adjacent vat 22, themounting means comprising pin or pivot 24, whereby said bars may be freeto rock about said pivot. The forward ends of bars 23 may be adapted tosupport the ends of shaft 25 which, in turn, carries roll 26, saidendsprojecting through apertures 25' provided in the side walls of vat 22.Apertures 25 may be relatively larger in diameter than shaft 25, so thatroll 26 may be adjustable a limited degree toward or away from roll II.To prevent excessive leakage of liquid through apertures 25, gaskets 26may be secured to each face of the side walls of the vat adjacent saidapertures, shaft 25 passing through the center of said gaskets. Gaskets26 may be constructed of flexible material such as rubber, leather orthe like. Roll 26 is adapted to be positioned within vat 22 and screenI3 together withweb I4 is adapted to pass between roll 26 and roll 20,the normal pressure of roll 26 against the screen and web beingcontrolledby weights 2'! which may be adjustably positioned along theopposite ends of bars 23. Roll 26 may be constructed of rubber or otherresilient material.

During the period that web I4 passes through the bath within vat 22, thetendency of said web is to expand, due to it being in the presence of anexcess of liquid. However, inasmuch as the web is confined betweenscreen I3 and the surface of roll I'I, substantial expansion ordistention of said web is prevented. As screen I3 and web I4 pass fromthe bath within vat 22, said screen and web passing between roll 26 androll II, the web is slightly compressed by the pressure of roll 26 uponthe screen and web. Immediately after passing between roll 26 and roll.I'I, web I4 is stripped or carried away from. the surface of roll I'I.Consequently, due to the tendency of the web to expand because of itspassing through the bath and due to the fact that the web is compressedbetween roll 26 and roll I1, the web when stripped, as has beenhereinbefore described, tends to expand as shown best at 23 in Fig. 3.

A pool 29 of th material constituting the bath accumulates at the nip ofthe rolls due to that tween rolls 26 and I1.

portion of the liquid carried out of the bath by screen 20, and also dueto the liquid absorbed by and adhering to web I4 being compressed be-When the web expands upon leaving the surface of screen 20, it canreadily be seen that said expansion takes place in the presence of pool29 and, therefore, liquid of the character constituting the bath isdrawn into said web, being distributed around and through the fibersconstituting the internal portion of the web. In addition, screen I3upon emerging from'the bath within vat 22 carries a quantity of theliquid constituting the bath upon its surface; When expansion takesplace at 28, the liquid upon said screen is also drawn into the web. Inthis manner, a relatively large quantity of the moisture originallypresent in the web is replaced by the liquid constituting the bath.

After emerging from vat 22, screen I3 carrying web I4 passes over guideroll 30 which may be journalled upon frame I, from whence the screen andweb are passed between squeeze rolls 3I and 32. Although a major portionof the expansion of web I4 after it leaves the bath takes place in thevicinity of the nip of rolls 26 and I1, expansion of web I4 continuesduring its passage from the bath to squeeze rolls 3i and 32. Hence,substantially all of the liquid adhering to the surface of web I4 andthe liquid which may adhere to the surface of screen I3 is drawn intothe interior of web I4.

Roll 3I may be mounted upon shaft 33 which may be journalled in frame Iand roll 32 may be mounted upon shaft 34 which may be carried by thefloating levers 35 which are, in turn, pivotally mounted at one end upon,frame I, as shown best at 36 in Fig. 1. The opposite end of levers 35may carry weights 3! which may be movably positioned along the length ofthe free end of said levers. A roll 38 may be mounted upon shaft 39,which, in turn, may be journalled in frame I, and an endless screen 40,of similar mesh to screen I3 may travel around rolls 32 and 38. Rolls 3Iand 32 exert normal pressure toward each other and inasmuch as screen I3and web I4 pass between said rolls, said web is squeezed or compressed,removing therefrom a quantity of the liquid, both that originallypresent in the web and also theliquid absorbed by said web from thebath. Rolls 3I and 32 are preferably covered with relatively soft rubberor other resilient material. In order to increase the duration of thesqueezing operation, web I4 after passage between rolls 3| and 32 may beconfined between screen I3 and screen 40 thereby permit- I ting theremoval of a desired quantity of liquid from web l4.

Screen I3 and web I4, after leaving rolls 3I and 32 and screen 40, passforwardly over drum 4I mounted on shaft 42 which, in turn, is journalledin frame I. An impregnating roll 43 may be mounted upon shaft 44 whichis journalled in bearing 45. Immediately beneath roll 43 a vat 46 ispositioned. Drum 4!, roll 43 and vat 46 may be similar in constructionrespectivelyto drum I5, roll II and vat 22. A- stripper roll 41 may bemounted within vat 46, the construction thereof and mounting meanstherefor being similar to that associated with roll 26.

Vat 46 is adapted to contain impregnating liquid with which it isdesired to further treat web I4. After passage over drum 4|, web I4 maybe carried between screen I3 and the foraminated surface of roll 43through the liquid comprising the bath. During passage through saidliquid, web I4 is again broughtinto intimate contact with the liquidimpregnating material. When leaving the bath, screen l3 and web l4 passbetween roll 41 and roll 43 whereby said web is compressed.Substantially immediately after leaving the nip of rolls 4'! and 43,said web expands in a manner similar to that which takes place after webl4 left the nip of rolls 26 and H. In so expanding, additionalimpregnating liquid is induced into the interior of web l4.

Screen l3 and web [4 after leaving rolls 43 and 47, pass over drum 48and are thence carried between squeeze rolls 49 and 50, which, similarto rolls 3| and 32, may be constructed of rubber or other resilientmaterial. Levers 5| may be pivoted at 52 to frame I, the opposite endsof said levers carrying weights 53. Roll 50 may be mounted upon shaft 54which, in turn, may be journalled at each end in levers 5|. Roll 49 maybe mounted upon shaft 55 which may be journalled in frame I. A shaft 56may also be journalled in frame I and may carry drum 51, and an endlessscreen 58 may be adapted to travel around roll so and drum 5'! in amanner similar to that described in conjunction with rolls 32 and 38.When screen l3 and web l4 pass between rolls 49 and 50 and said web inits further progress is confined between screen l3 and screen 58, theexcess impregnating material accumulated by web it during its passagethrough vat 46 is removed.

Screen i3 and web I4, after passing from rolls is and 5e, are carriedover drum 59 and are thereafter passed between rolls 60 and 6 I. Roll Hmay be mounted upon shaft 62 which may be journalied in bearing 63mounted on lever 64. Lever 64 may be pivoted at one end, as at 65, to aportion of frame I. A bracket 66 may extend from a lower end portion offrame I and member 61 may be pivoted thereto as at 68. Member 61 maycarry an extension 59 upon which may be mounted a movable weight iii. Arod 1| may connect the free end of lever 64 and an intermediate portionof the assembly comprising member 61 and extension 69, the effectivelength of said rod being variable by means of conical nut 12 and handwheel it, which are respectively threadedly positioned at the lower'andupper end of rod H The arrangement issuch that the normal pressure ofroll Bl upon roll 60 may be changed by changing the position of weight10 along the length of extension 69.

After passage of screen l3 and web l4 between rolls 60 and 6!, web l4may be stripped from screen l3 and said screen may be carried aroundroll 80 and returned over guide rolls [3, 14, l5, l8, ll, l8, 19, 8D and8| to roll l2, all of said guide rolls being mounted at the lowerportion of frame l. Web I 4, when stripped from screen l3 may, ifdesired, be wound upon roll 6|, said roll functioning in this instanceas a make-up roll. The various layers wound upon roll 6!, in this case,may be stripped therefrom in multi-ply sheets. If desired, however, webl4 may be stripped from screen l3 after passage between rolls 6:) and6|, and may be carried to a battery of conventional drum dryers (notshown).

A pan 82 may bepositioned beneath rolls 3| and 32 to retrieve the liquidexpressed from the web by said rolls. Similarly, pans 83 and 84 may bepositioned beneath rails 49 and 59 and 60 and BI, respectively.

It is to be understood, of course, that although two impregnating andsqueezing units are shown and described inftandem relationship with eachother. as many units as desired may be used depending upon the degree ofimpregnation desired. the type of impregnating material, the speed ofoperation or the characteristics of the web both as to the properties ofthe fibers constituting the web and the original moisture content of theweb. It is also to be understood that, in using multiple impregnatingand squeezing units in tandem, the supporting screen need not be acontinuous screen which is carried through all of the units. Forinstance, an individual endless screen may be utilized in conjunctionwith each impregnating and squeezing unit, in which case the web afterleaving one squeezing unit will be stripped from the screen associatedwith that unit and passed to the screen of the next succeeding unit.

The use of one endless supporting screen for a plurality of impregnatingand squeezing units may be utilized in those instances where themaintenance of the exact concentration in the various vats is notessential, as in the case where all of the saturating baths contain thesame saturant or with different concentrations of the same saturantwhere slight variations in concentration are unimportant. The multipleseparate units with individual supporting screens for eachunit may bedesirable where the various saturating baths are not the same and mustbe kept separate as, for example, in the case where it may be desired tofill a web with a relatively inexpensive off-color filler and finish thesurface as a last operation with a high grade pigment.

I have used the term saturate with both emulsions and suspensions ofliquids and solids. It should be realized however, that the coarser theparticles are the less mobile the particles are as regards their travelwith the liquid medium with which they tend to move. Thus fillersuspensions While capable of being carried along with a liquid whilebeing prevented from falling therethrough, are much less mobile and notso much a part of the liquid as for example a fine oil emulsion, due totheir size, relatively greater density and their non-spherical shape. Inthe methods and for the purposes of this invention they may, however, beclassed with the more mobile water combinations, provided it is clearthat the physical condition of the coarser solid suspensions bringsabout certain variations from the more perfect distribution describedand obtained with the more mobile combinations. Thus, for example, thereis a decided tendency for filler suspensions to filter out to someextent on the surface of a fine web while the same filler suspension mayeasily enter a more open web. However, by the use of a succession ofdips in filler suspension and intermediate couchings a the fillerremaining on the surface of the web is driven through the body of theweb by the previously described "breathing of the web under compressionand decompression in the presence of its water content and the fillerparticles. This relatively sluggish action may be used, therefore, tofill a web with a cheaper filler and finish the surfaces with a. moreexpensive one. It should be noted that the effect of introducing fillerby this method is not a coating and covering of the fibres as occurs inordinary coated paper but a deposition of the filler in the plane of thesurface fibres and beneath them. Such a'positioning of thefillers'results in a non-cracking tough filled surface, and as describedisa substantial equivalent of coated paper obtained in a singleoperation concomitant with the paper making itself. The quantity offiller introduced is variable between wide limits, the upper limit ofwhich may he great'e'fthan 50% of the total weight of the paper. Also,the separated multiple arrangement may be used where it is desired toconduct several chemical treatments in tandem. For example, 5 apartially hydrated sulphite web may be passed -first into a bathcontaining cold concentrated caustic soda to form a partial sodacellulose, through a second bath containing emulsified carbondi-sulphide which will react with the partly formed soda cellulose toproduce a partial viscose, then through an intermediate warming box andthrough a third bath containing a hot salt solution to set the viscosepreviously formed and then through a fourth and fifth unit containinghot water to wash out the salts of inter-action. The web thereuponpasses through dryers, super calenders and friction calenders. Theresult of such a procedure is to form a sheet containing amorphouscellulose derived from the viscose formed by the above steps,-whichamorphous cellulose acts as a binder for the ungelatinized innerportions of the fibres, giving the effect of very highly hydratedcellulose fibres. The super-calendering breaks down the previouslyuntreated fibre and the final effect is to produce a sheet substantiallytransparenta product between the old glassine paper and the "cellophaneof today. This example is given to show the possibilities of multipletreatment of wet webs by the use of the wet web saturating machines intandem in a continuous process.

The machine also has utility as a washer for a wet web wherebyundesirable soluble materials may be removed from a wet web beforedrying the web. For example, acid introduced in the beater forprecipitation of sizing materials, which causes deterioration of paper,may be almost completely removed by washing and then the remaining acidneutralized in a dilute ammonia bath. Conducting salts undesirable inelectrical insulating paper may be similarly washed out. The sameoperations which substitute saturants for water originally present inthe web may thus be used to substitute pure water for impure water.

It is to be understood also, that although my invention is particularlyadaptable for saturating, coating or sizing a wet fibrous web, it mayalso be used for other purposes. Broadly, the invention is adaptable foruse wherever it is desired to supplant or replace a portion orsubstantially all of the original moisture content of a wet fibrous webwith another liquid having different characteristics. From the foregoingit will be apparent that I have provided a novel form of device forhandling the difficult combinations hereinbefore referred to to producefull, uniform saturation of wet webs whether the web be dense or loose,whether the saturant be viscous or mobile, or in the form of a sluggishsuspension or emulsion, and at any desired speed, merely by multiplyingthe number of operations similar to the single operation described insaid cU-pending application and operating so as to produce distentionand saturation of the web in each saturating unit, as described above.It also provides a means of insuring displacement of the water and airoriginally contained in the wet web with an aqueous liquid containing aselected modifying material.

It may be desirable in some cases where the web is especially dense andit is desired to intro- 75 duce a relatively viscous saturant orsluggish suspension, to start the saturation with a more easilysaturatable saturant of the composition desired, making certain that inthe first bath saturation and distention take place, which saturation isthoroughly distributed by the follow- 5 ing couching, increasing theconcentration with each progressive saturation or impregnation until therequired amount has been introduced into the web.

It is also a characteristic of multiple satura- 10 tion and intermediatecouching', according to the present invention, that almost any desirableamount of filler may be worked into a wet web. It is characteristic offillers, unlike dissolved saturants, that they tend to remain entangled5 in the web on passage through squeeze rolls, and on further saturationand couching add successivcly to the amount of filler contained in theweb. Thus, a quantity of filler greatly in ex- .cess of proportionsobtainable by beater processes may be efficiently and evenly' introducedinto a paper web, producing filled papers of greater smoothness andopacity than heretofore produced without surface coating.

In the field of waxed papers a quantity of 25 paraffin wax or oilemulsion may be introduced, according to the present invention,suiiicient to make the paper translucent on drying, which has not.heretofore been possible by introduction into the beater because of lowretention. 30

It is an essential of the multiple process described when obtainingthorough impregnation in the final web that each step beginning with thefirst, must result in material distention of the wet web andintroduction and distribution of the 35 saturant to be introduced inthat step. In other words, an imperfection of distribution, or a coatingof the web in any one step as against impregnation, results in laterimperfection of distribution and is therefore to be avoided. 40

I claim as my invention:

1. The combination with means for forming a wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units, each 45 unit comprising animpregnating device and a squeezing device, and flexible foraminatedmeans associated with said units for positively supporting and conveyingthe wet fibrous web through said units in seriatim.

2. The combination with means for forming a wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units, each unit comprising animpregnating device and 55 a squeezing device, each impregnating devicecomprising a vat for liquid impregnating material.

a roll having a foraminated surface rotatably positioned in said vat,flexible foraminated means associated with said units for positivelysupporting and conveying the wet fibrous web through said units inseriatim, and means for confining said web passing through theimpregnating device between said foraminated means and the foraminatedsurface of said roll.

3. The combination with means for forming a. wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units, each unit comprising animpregnating device and a squeezing device, each impregnating devicecomprising a vat for liquid impregnating material, a roll having aforaminated surface rotatably positioned in said vat, flexibleforaminated means associated with said units for positively supportingand conveying the wet fibrous web through said units in seriatim, meansfor confining said web when passing through the impregnating devicesbetween said foraminated means and the foraminated surfaces of saidrolls, and a couch roll mounted in each vat which the web passes intraveling through said impregnating devices.

4. The combination with means for forming a wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units, each comprising animpregnating device and a squeezing device, each impregnating devicecomprising a vat for liquid impregnating material, a roll having aforaminated surface rotatably positioned in said vat, flexibleforaminated means associated with said units for positively supportingand conveying the wet fibrous web through said units in seriatim, andmeans for confining said web when passing through the impregnatingdevices between said foraminated means and the foraminated surfaces ofsaid rolls, a couch roll mounted in each vat which the web passes intraveling through said impregnating devices, each of said squeezingdevices comprising a pair of juxtaposed rolls between which saidforaminated means and said web pass after leaving each impregnatingdevice whereby said web is compressed and the excess liquid containedtherein is removed.

5. The combination with means for forming a wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units disposed in tandem, anendless screen adapted to pass through and carry the wet fibrous webthrough said units in seriatim, said screen supporting the web duringsuch passage, each treating unit comprising an impregnating device and asqueezing device alternately positioned in the path of travel of thescreen and web.

6. The raombination with means for forming a wet felted fibrous web, ofmeans for impregnating said wet web with a permeating liquid comprisinga plurality of individual impregnating units disposed in tandem, anendless screen adapted to pass through and carry the wet fibrous webthrough said units in seriatim, said screen supporting the web duringsuch passage, each treating unit comprising an impregnating device and asqueezing device alternately positioned in the path of travel of thescreen and web, each of said impregnating devices comprising a, vat forimpregnating liquid, a roll having a foraminated surface positioned torotate in said vat, means for carrying said web into the liquid in saidvat con fined between said screen and the surface of the roll, and meansfor couching said web in the presence of an excess of impregnatingliquid as it emerges from the liquid in said vat.

7. The combination with means for forming a. wet felted fibrous web, ofmeans for impregnating said wet web with a, permeating liquid comprisinga plurality of individual impregnating units disposed in tandem, anendless screen adapted to pass through said units and carry a fibrousweb therethrough, said screen supporting the web during such passage,each treating unit comprising an impregnating device and a squeezingdevice alternately positioned in the path of travel of the screen andweb, each of said squeezing devices comprising a pair of juxtaposedrolls having resilient surfaces, and means for passing said screen andweb after the web is couched in the impregnating device between saidresilient surfaced rolls.

IZADOR J. NOVAK.

